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Impact of initial fluctuations and nuclear deformations in isobar collisions
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作者 Jian-Fei Wang Hao-Jie Xu Fu-Qiang Wang 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第6期155-162,共8页
Relativistic isobar^(96)_(44)Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zrcollisions have revealed intricate differences in their nuclear size and shape,inspiring unconventional studies of nuclear structure using relat... Relativistic isobar^(96)_(44)Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zrcollisions have revealed intricate differences in their nuclear size and shape,inspiring unconventional studies of nuclear structure using relativistic heavy ion collisions.In this study,we investigate the relative differences in the mean multiplicityR_(<Nch>)and the secondR_(ε2)and third-order eccentricityR_(ε3)between isobar collisions using initial state Glauber models.It is found that initial fluctuations and nuclear deformations have negligible effects on R_(<Nch>)in most central collisions,while both are important for the R_(ε2)and R_(ε3),the degree of which is sensitive to the underlying nucleonic or sub-nucleonic degree of freedom.These features,compared to real data,may probe the particle production mechanism and the physics underlying nuclear structure. 展开更多
关键词 Relativistic isobar collisions Initial fluctuations Nuclear deformation
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Optimization of Gas Production from Hydrate-Bearing Sediments with Fluctuation Characteristics
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作者 LI Yaobin XU Tianfu +3 位作者 XIN Xin YU Han YUAN Yilong ZHU Huixing 《Journal of Ocean University of China》 SCIE CAS CSCD 2024年第3期618-632,共15页
As an important source of low-carbon,clean fossil energy,natural gas hydrate plays an important role in improving the global energy consumption structure.Developing the hydrate industry in the South China Sea is impor... As an important source of low-carbon,clean fossil energy,natural gas hydrate plays an important role in improving the global energy consumption structure.Developing the hydrate industry in the South China Sea is important to achieving‘carbon peak and carbon neutrality’goals as soon as possible.Deep-water areas subjected to the action of long-term stress and tectonic movement have developed complex and volatile terrains,and as such,the morphologies of hydrate-bearing sediments(HBSs)fluctuate correspondingly.The key to numerically simulating HBS morphologies is the establishment of the conceptual model,which represents the objective and real description of the actual geological body.However,current numerical simulation models have characterized HBSs into horizontal strata without considering the fluctuation characteristics.Simply representing the HBS as a horizontal element reduces simulation accuracy.Therefore,the commonly used horizontal HBS model and a model considering the HBS’s fluctuation characteristics with the data of the SH2 site in the Shenhu Sea area were first constructed in this paper.Then,their production behaviors were compared,and the huge impact of the fluctuation characteristics on HBS production was determined.On this basis,the key parameters affecting the depressurization production of the fluctuating HBSs were studied and optimized.The research results show that the fluctuation characteristics have an obvious influence on the hydrate production of HBSs by affecting their temperatures and pressure distributions,as well as the transmission of the pressure drop and methane gas discharge.Furthermore,the results show that the gas productivity of fluctuating HBSs was about 5%less than that of horizontal HBSs.By optimizing the depressurization amplitude,well length,and layout location of vertical wells,the productivity of fluctuating HBSs increased by about 56.6%. 展开更多
关键词 natural gas hydrate numerical simulation fluctuation characteristics depressurization production production well optimization
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Altered spontaneous brain activity patterns in hypertensive retinopathy using fractional amplitude of low-frequency fluctuations:a functional magnetic resonance imaging study
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作者 Xue-Lin Wang Xu-Jun Zheng +8 位作者 Li-Juan Zhang Jin-Yu Hu Hong Wei Qian Ling Liang-Qi He Cheng Chen Yi-Xin Wang Xu Chen Yi Shao 《International Journal of Ophthalmology(English edition)》 SCIE CAS 2024年第9期1665-1674,共10页
AIM:To study functional brain abnormalities in patients with hypertensive retinopathy(HR)and to discuss the pathophysiological mechanisms of HR by fractional amplitude of low-frequency fluctuations(fALFFs)method.METHO... AIM:To study functional brain abnormalities in patients with hypertensive retinopathy(HR)and to discuss the pathophysiological mechanisms of HR by fractional amplitude of low-frequency fluctuations(fALFFs)method.METHODS:Twenty HR patients and 20 healthy controls(HCs)were respectively recruited.The age,gender,and educational background characteristics of the two groups were similar.After functional magnetic resonance imaging(fMRI)scanning,the subjects’spontaneous brain activity was evaluated with the fALFF method.Receiver operating characteristic(ROC)curve analysis was used to classify the data.Further,we used Pearson’s correlation analysis to explore the relationship between fALFF values in specific brain regions and clinical behaviors in patients with HR.RESULTS:The brain areas of the HR group with lower fALFF values than HCs were the right orbital part of the middle frontal gyrus(RO-MFG)and right lingual gyrus.In contrast,the values of fALFFs in the left middle temporal gyrus(MTG),left superior temporal pole(STP),left middle frontal gyrus(MFG),left superior marginal gyrus(SMG),left superior parietal lobule(SPL),and right supplementary motor area(SMA)were higher in the HR group.The results of a t-test showed that the average values of fALFFs were statistically significantly different in the HR group and HC group(P<0.001).The fALFF values of the left middle frontal gyrus in HR patients were positively correlated with anxiety scores(r=0.9232;P<0.0001)and depression scores(r=0.9682;P<0.0001).CONCLUSION:fALFF values in multiple brain regions of HR patients are abnormal,suggesting that these brain regions in HR patients may be dysfunctional,which may help to reveal the pathophysiological mechanisms of HR. 展开更多
关键词 hypertensive retinopathy fractional amplitude of low-frequency fluctuation brain region magnetic resonance imaging
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Experimental study on temperature fluctuations on plate surface induced by coaxial-jet flow
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作者 Xue-Yao Xiong Zun-Quan Liu +2 位作者 Guo-Yan Zhou Xing Luo Shan-Tung Tu 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第5期139-153,共15页
In nuclear reactors,temperature fluctuations of fluids may cause fatigue damage to adjacent structures;this is referred to as thermal striping.Research on thermal striping in the upper plenum has mainly focused on flu... In nuclear reactors,temperature fluctuations of fluids may cause fatigue damage to adjacent structures;this is referred to as thermal striping.Research on thermal striping in the upper plenum has mainly focused on fluid fields.Few experimental studies have been reported on solid structures in a fluid field with a coaxial jet.This study entailed an experimental study of the temperature fluctuations in the fluid and on a plate surface caused by a coaxial jet.The temperature fluctuations of the fluid and plate surfaces located at different heights were analyzed.The cause of the temperature fluctuation was analyzed using a transient temperature distribution.The results show that the mixing of the hot and cold fluids gradually becomes uniform in the positive axial direction.The average surface temperatures tended to be consistent.When the jet reaches the plate surface,the swing of the jet center,contraction and expansion of the cold jet,and changes in the jet shape result in temperature fluctuations.The intensity of the temperature fluctuation was affected by the position.More attention should be paid when the plate is located at a lower height,and between the hot and cold-fluid nozzles. 展开更多
关键词 Temperature fluctuation Thermal striping Coaxial jet Thermal mixing The upper plenum of nuclear reactor
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Research on Anti-Fluctuation Control of Winding Tension System Based on Feedforward Compensation
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作者 Yujie Duan Jianguo Liang +4 位作者 Jianglin Liu Haifeng Gao Yinhui Li Jinzhu Zhang Xinyu Wen 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第5期1239-1261,共23页
In the fiber winding process,strong disturbance,uncertainty,strong coupling,and fiber friction complicate the winding constant tension control.In order to effectively reduce the influence of these problems on the tens... In the fiber winding process,strong disturbance,uncertainty,strong coupling,and fiber friction complicate the winding constant tension control.In order to effectively reduce the influence of these problems on the tension output,this paper proposed a tension fluctuation rejection strategy based on feedforward compensation.In addition to the bias harmonic curve of the unknown state,the tension fluctuation also contains the influence of bounded noise.A tension fluctuation observer(TFO)is designed to cancel the uncertain periodic signal,in which the frequency generator is used to estimate the critical parameter information.Then,the fluctuation signal is reconstructed by a third-order auxiliary filter.The estimated signal feedforward compensates for the actual tension fluctuation.Furthermore,a time-varying parameters fractional-order PID controller(TPFOPID)is realized to attenuate the bounded noise in the fluctuation.Finally,TPFOPID is enhanced by TFO and applied to control a tension control system considering multi-source disturbances.The stability of the method is analyzed by using the Lyapunov theorem.Finally,numerical simulations verify that the proposed scheme improves the tracking ability and robustness of the system in response to tension fluctuations. 展开更多
关键词 Constant tension control anti-fluctuation strategy tension fluctuation observer time-varying parameters fractional-order PID controller feedforward compensate
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Influence of blood glucose fluctuations on chemotherapy efficacy and safety in type 2 diabetes mellitus patients complicated with lung carcinoma
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作者 Tian-Zheng Fang Xian-Qiao Wu +4 位作者 Ting-Qi Zhao Shan-Shan Wang Guo-Mei-Zhi Fu Qing-Long Wu Cheng-Wei Zhou 《World Journal of Diabetes》 SCIE 2024年第4期645-653,共9页
BACKGROUND Patients with type 2 diabetes mellitus(T2DM)have large fluctuations in blood glucose(BG),abnormal metabolic function and low immunity to varying degrees,which increases the risk of malignant tumor diseases ... BACKGROUND Patients with type 2 diabetes mellitus(T2DM)have large fluctuations in blood glucose(BG),abnormal metabolic function and low immunity to varying degrees,which increases the risk of malignant tumor diseases and affects the efficacy of tumor chemotherapy.Controlling hyperglycemia may have important therapeutic implications for cancer patients.AIM To clarify the influence of BG fluctuations on chemotherapy efficacy and safety in T2DM patients complicated with lung carcinoma(LC).METHODS The clinical data of 60 T2DM+LC patients who presented to the First Affiliated Hospital of Ningbo University between January 2019 and January 2021 were retrospectively analyzed.All patients underwent chemotherapy and were grouped as a control group(CG;normal BG fluctuation with a mean fluctuation<3.9 mmol/L)and an observation group(OG;high BG fluctuation with a mean fluctuation≥3.9 mmol/L)based on their BG fluctuations,with 30 cases each.BGrelated indices,tumor markers,serum inflammatory cytokines and adverse reactions were comparatively analyzed.Pearson correlation analysis was performed to analyze the correlation between BG fluctuations and tumor markers.RESULTS The fasting blood glucose and 2-hour postprandial blood glucose levels in the OG were notably elevated compared with those in the CG,together with markedly higher mean amplitude of glycemic excursions(MAGE),mean of daily differences,largest amplitude of glycemic excursions and standard deviation of blood glucose(P<0.05).In addition,the OG exhibited evidently higher levels of carbohydrate antigen 19-9,carbohydrate antigen 125,carcinoembryonic antigen,neuron-specific enolase,cytokeratin 19,tumor necrosis factor-α,interleukin-6,and highsensitivity C-reactive protein than the CG(P<0.05).Pearson analysis revealed a positive association of MAGE with serum tumor markers.The incidence of adverse reactions was significantly higher in the OG than in the CG(P<0.05).CONCLUSION The greater the BG fluctuation in LC patients after chemotherapy,the more unfavorable the therapeutic effect of chemotherapy;the higher the level of tumor markers and inflammatory cytokines,the more adverse reactions the patient experiences. 展开更多
关键词 Blood glucose fluctuation Type 2 diabetes mellitus Lung carcinoma Tumor markers
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A Statistical Method for Characterizing CMOS Process Fluctuations in Subthreshold Current Mirrors 被引量:2
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作者 张雷 余志平 贺祥庆 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第1期82-87,共6页
A novel method to characterize CMOS process fluctuations in subthreshold current mirrors (SCM) is reported. The proposed model is succinct in methodology and calculation complexity compared with previous statistical... A novel method to characterize CMOS process fluctuations in subthreshold current mirrors (SCM) is reported. The proposed model is succinct in methodology and calculation complexity compared with previous statistical models. However,it provides favorable estimations of CMOS process fluctuations on the SCM circuit, which makes it promising for engineering applications. The model statistically abstracts physical parameters, which depend on the IC process, into random variables with certain mean values and standard deviations, while aggregating all the random impacts into a discrete martingale. The correctness of the proposed method is experimentally verified on an SCM circuit implemented in an SMIC 0.18μm CMOS 1P6M mixed signal process with a conversion factor of 100 in an input range from 100pA to lμA. The pro- posed theory successfully predicts - 10% of die-to-die fluctuation measured in the experiment, and also suggests the -lmV of threshold voltage standard deviation over a single die,which meets the process parameters suggested by the design kit from the foundry. The deviations between calculated probabilities and measured data are less than 8%. Meanwhile, pertinent suggestions concerning high fluctuation tolerance subthreshold analog circuit design are also made and discussed. 展开更多
关键词 CMOS process fluctuations subthreshold current mirror random variable PROBABILITY discrete martingale
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Effects of salinity fluctuation and dietary protein/ carbohydrate ratio on the survival and growth of Juvenile Litopenaeus vannamei 被引量:1
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作者 王兴强 曹梅 阎斌伦 《Marine Science Bulletin》 CAS 2010年第2期61-73,共13页
A factorial study was conducted to determine the effects of salinity (constant (SO) and fluctuating (S10)) and isoenergetic diet of different protein/carbohydrate ratios (P/C: 4.1, 1.9, 1.0 and 0.6) on the su... A factorial study was conducted to determine the effects of salinity (constant (SO) and fluctuating (S10)) and isoenergetic diet of different protein/carbohydrate ratios (P/C: 4.1, 1.9, 1.0 and 0.6) on the survival and growth of juvenile Litopenaeus vannamei. The experiment lasted for 35 days. The results showed that I) At S0 and S10, specific growth rate and apparent digestibility coefficient exhibited decreasing trend, while food conversion ratio exhibited increasing trend, with decreasing P/C ratio. At SO, food consumption and specific growth rate of the shrimp fed 4.1 P/C were significantly higher than those fed 1.0 and 0.6 P/C, whereas at S10, no significant differences were detected among different treatments; II) At 4.1 and 1.9 P/C, food consumption and specific growth rate were higher in the shrimp maintained at SO as compared with those at S10, while at 1.0 and 0.6 P/C, an inverse trend was observed. Among four P/C ratios, food conversion ratio of the shrimp at SO was the lowest. 展开更多
关键词 Litopenaeus vannamei salinity fluctuation protein/carbohydrate ratio SURVIVAL growth
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New seismic attribute:Fractal scaling exponent based on gray detrended fluctuation analysis 被引量:1
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作者 黄亚平 耿建华 郭彤楼 《Applied Geophysics》 SCIE CSCD 2015年第3期343-352,467,共11页
Seismic attributes have been widely used in oil and gas exploration and development. However, owing to the complexity of seismic wave propagation in subsurface media, the limitations of the seismic data acquisition sy... Seismic attributes have been widely used in oil and gas exploration and development. However, owing to the complexity of seismic wave propagation in subsurface media, the limitations of the seismic data acquisition system, and noise interference, seismic attributes for seismic data interpretation have uncertainties. Especially, the antinoise ability of seismic attributes directly affects the reliability of seismic interpretations. Gray system theory is used in time series to minimize data randomness and increase data regularity. Detrended fluctuation analysis (DFA) can effectively reduce extrinsic data tendencies. In this study, by combining gray system theory and DFA, we propose a new method called gray detrended fluctuation analysis (GDFA) for calculating the fractal scaling exponent. We consider nonlinear time series generated by the Weierstrass function and add random noise to actual seismic data. Moreover, we discuss the antinoise ability of the fractal scaling exponent based on GDFA. The results suggest that the fractal scaling exponent calculated using the proposed method has good antinoise ability. We apply the proposed method to 3D poststack migration seismic data from southern China and compare fractal scaling exponents calculated using DFA and GDFA. The results suggest that the use of the GDFA-calculated fractal scaling exponent as a seismic attribute can match the known distribution of sedimentary facies. 展开更多
关键词 Seismic attribute gray system theory detrended fluctuation analysis fractal scaling exponent
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Effects of Salinity Fluctuation and Dietary Traditional Chinese Herbal Medicines on Survival,Growth and Immunity of Exopalaemon carinicauda 被引量:1
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作者 曹梅 王兴强 +2 位作者 阎斌伦 张庆起 高景锋 《Agricultural Science & Technology》 CAS 2010年第1期77-81,102,共6页
[Objective]The aim of this study was to provide a theoretical basis for the large-scale breeding of Exopalaemon carinicauda. [Method]Effects of salinity fluctuation (S0,S3,S6 and S9 represented salinity fluctuations ... [Objective]The aim of this study was to provide a theoretical basis for the large-scale breeding of Exopalaemon carinicauda. [Method]Effects of salinity fluctuation (S0,S3,S6 and S9 represented salinity fluctuations of 0,3,6 and 9 respectivley) and dietary traditional Chinese herbal medicines (0,1%,2% and 4% respectively) on survival,growth and immunity of E.carinicauda were studied,and its experiment lasted for 60 d. [Result]The results showed that specific growth rate,feed conversion efficiency and superoxide dismutase activity of E.carinicauda in the treatment group with 1% dietary traditional Chinese herbal medicine and S6 salinity fluctuation were higher than those in other treatments,which was significantly higher than the treatment groups with S0,S3 and S9 salinity fluctuation at the same adding level of 1% dietary traditional Chinese herbal medicine. The regression analysis indicated that at S0,S3 and S6 salinity fluctuation,the optimal adding level of dietary traditional Chinese herbal medicines in feeds decreased with the increase of salinity fluctuation,accounting for 2.74%,1.77% and 0.51% respectively. At four adding levels of dietary traditional Chinese herbal medicines,the optimal salinity fluctuation of E.carinicauda also decreased with the increase of dietary traditional Chinese herbal medicines in feeds,accounting for 5.26,4.95,3.54 and 1.97 respectively. [Conclusion]Salinity,dietary traditional Chinese herbal medicines and their interactions have a significant effect on survival,growth and immunity of E.carinicauda,which calls for attentions in the breeding. 展开更多
关键词 Exopalaemon carinicauda Salinity fluctuation Dietary traditional Chinese herbal medicines SURVIVAL GROWTH IMMUNITY
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Main Diseases and Pests of Lonicerae japonica in Guangxi Province and Fluctuation Pattern of Their Natural Enemies
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作者 欧善生 苏桂花 +8 位作者 谢恩倍 覃连红 简峰 黄雪兰 石化玉 黄奉茂 陈彩贤 王小欣 黄艳花 《Plant Diseases and Pests》 CAS 2011年第3期31-34,38,共5页
[ Objective ] The paper was to study the main diseases and pests in Lonicerae japonica in Guangxi Province and fluctuation pattern of their natural ene- mies. [Method] The population change of main diseases and pests,... [ Objective ] The paper was to study the main diseases and pests in Lonicerae japonica in Guangxi Province and fluctuation pattern of their natural ene- mies. [Method] The population change of main diseases and pests, and main predatory naturaI enemies of pests in different species of Lonicerae japonica in Xincheng County of Guangxi Province were systematically investigated during 2008 -2010. [ Result ] The variation cycle of population number of Semiaphis heraclei (Takahashi) belongs to single peak type, and it has large occurrence in April. The variation cycle of population number of Franklinlella sp. and Haptonchus luteo- ius (Erichson) belongs to double peak type, and they have large occurrence at April and September. The variation cycle of disease severity of Microsphaera lonicerae ( Wint. ) belongs to double peak type, and the disease index will be larger at April and September. The variation cycle of diseased shoot rate belongs to single peak type; diseased shoot rote of Lonicera dasystyla Rehd. and Loniccra hvpolzlauca Miquel is relatively high during April to June, while the index of Lonice- ra confusa (Sweet) DC. is relatively high during February to May. The variation cycle of population number of main natural enemies such as Lemnia biplagiata ( Swartz), Coccinella septcmpunctata ( Linnaeus ) and Harmonia axyridis (Pallas) belongs to double peak type, and they have large occurrence at April and Sep- tember. [ Conclusion] The results could provide scientific basis for determination of optimum control period against major diseases and pests in Loniceraejaponica and development of integrated control programs. 展开更多
关键词 Lonicerae japonica Pests and diseases ENZYME fluctuation pattern China
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Analysis and Pollution Assessment on the Dissolved Organic Matter in the Sediment of Hydro-fluctuation Belt(Yunyang Part) 被引量:2
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作者 来守军 关晓琳 +3 位作者 陈飞 蒋琴 莫谍谍 付川 《Meteorological and Environmental Research》 CAS 2010年第8期98-101,共4页
By using the ultraviolet absorption spectrum,the fluorescence spectrum and three dimensional fluorescence spectra,the composition of dissolved organic matter(DOM) and the humification degree,etc.in the sediment of hyd... By using the ultraviolet absorption spectrum,the fluorescence spectrum and three dimensional fluorescence spectra,the composition of dissolved organic matter(DOM) and the humification degree,etc.in the sediment of hydro-fluctuation belt(Yunyang part) were analyzed.The relationship between the test parameters and the pollution degree in the region was discussed.The research results of UV spectrum data E3/E4 showed that in 4 sampling sites which included Huangshi Town,Gaoyang Town,Shuangjiang Town and Quma Town,the humification degree in the sediment of hydro-fluctuation belt in Shuangjiang Town sampling site was lower,and the aromaticity was smaller.Moreover,the effect of human factor was comparatively smaller.The fluorescence index value which represented the source of humus in DOM was 1.62-1.88.It showed that the biological and terrestrial source both existed.Three dimensional spectra results showed that the pollution degrees in 4 sampling sites were all smaller,and some prevention measures should be taken early. 展开更多
关键词 Hydro-fluctuation belt SEDIMENT Dissolved organic matter Analysis and assessment China
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Zero-Point Energy and Fluctuation in a Field-Josephson Junction-Coupled System
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作者 邵彬 邹健 李前树 《Journal of Beijing Institute of Technology》 EI CAS 2000年第2期142-147,共6页
To investigate the interaction of a mesoscopic Josephson junction with a single mode quantized electromagnetic field, the diagnonalizing process of the coupled system Hamiltonian was performed by using an unitary tran... To investigate the interaction of a mesoscopic Josephson junction with a single mode quantized electromagnetic field, the diagnonalizing process of the coupled system Hamiltonian was performed by using an unitary transformation. Zero? point energy and zero? point fluctuation of the coupled system were shown. For the ground state of the coupled system, the quantum fluctuations of the flux and charge operators in the field and junction subsystems can exhibit smaller quantum noise than the zero point fluctuations of the individual subsystems. Thus, when the coupled system is in its lowest energy state, which means that no radiation appear, the two subsystems exhibit nonclassical behavior. 展开更多
关键词 fluctuation mesoscopic Josephson junction SQUEEZING
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New Way to Quantize Time-Dependent RLC Electric Circuit and Quantum Fluctuations
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作者 梁麦林 袁兵 赵林 《Transactions of Tianjin University》 EI CAS 2002年第1期8-11,共4页
According to the physical mechanism of the generation of the resistance or the electron phonon interaction, a new method is proposed to quantize the RLC electric circuit. Calculations show that the quantum fluctuatio... According to the physical mechanism of the generation of the resistance or the electron phonon interaction, a new method is proposed to quantize the RLC electric circuit. Calculations show that the quantum fluctuations under this new quantization are smaller than those by the traditional effective Hamiltonian method. And squeezed states can be generated if the inductance and capacity are time dependent. Meanwhile, the shortcoming of the traditional method that the electric charge and current will vanish in the long time limit is overcome. 展开更多
关键词 RLC electric circuit lattice oscillation quantum fluctuation squeezed state
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Research on the Agglomeration and Fluctuation Situation of Rice Production in Hunan Province
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作者 邓文 杨玉 《Agricultural Science & Technology》 CAS 2011年第10期1405-1410,共6页
[Objective] This paper aimed at studying the agglomeration and fluctuation situation of rice production in Hunan Province during the past 10 years.[Method] Data were collected from Hunan Rural Statistical Yearbook(20... [Objective] This paper aimed at studying the agglomeration and fluctuation situation of rice production in Hunan Province during the past 10 years.[Method] Data were collected from Hunan Rural Statistical Yearbook(2001-2010).Taking the concentration index of sown area and production(CDI) and the volatility index(VI) as the main indicators,the agglomeration and fluctuation situation of paddy rice,early-season rice,middle-season rice and single-season late rice,late-season rice,good quality early-season rice,good quality middle-season rice and good quality single-season late rice,good quality late-season rice production in each major rice-producing area of Hunan Province during the past 10 years had been studied.[Result] The orders of concentration index of sown areas and production of paddy rice,early-season rice,middle-season rice and single-season late rice,late-season rice,good quality early-season rice,good quality middle-season rice and good quality single-season late rice,good quality late-season rice in Hunan Province varied,but the orders of volatility index were consistent.The stable areas,relatively stable areas and fluctuant areas in sown areas and production of different major rice-producing areas were defined.[Conclusion] The research had provided basis for optimizing the layout of rice production in Hunan Province,promoting agglomeration and development of rice production and translating the comparative advantages into the competitive advantages. 展开更多
关键词 RICE AGGLOMERATION fluctuation Hunan Province
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An Interpretation on Jig's Psychological Fluctuations in Hills like White Elephants
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作者 周东妮 杨雪霁 《海外英语》 2014年第11X期215-216,共2页
Hills like White Elephants is one of the masterpieces of Ernest Hemingway. The story bears an open ending. This paper attempts to analyze the heroine-Jig's psychological fluctuations, and her three emotional stage... Hills like White Elephants is one of the masterpieces of Ernest Hemingway. The story bears an open ending. This paper attempts to analyze the heroine-Jig's psychological fluctuations, and her three emotional stages to support the author's interpretation on the end of the story—the heroine's final decision is to have the baby born. 展开更多
关键词 INTERPRETATION PSYCHOLOGICAL fluctuationS Hills LI
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Fluctuation Resonance of Feed Forward Loops in Gene Regulatory Networks 被引量:1
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作者 董翊 侯中怀 辛厚文 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2009年第4期359-365,447,共8页
The feed forward loop (FFL), wherein a gene X can regulate target gene Z alone or cooperatively with gene Y, is one of the most important motifs in gene regulatory networks. Gene expression often involves a small nu... The feed forward loop (FFL), wherein a gene X can regulate target gene Z alone or cooperatively with gene Y, is one of the most important motifs in gene regulatory networks. Gene expression often involves a small number of reactant molecules and thus internal molecular fluctuation is considerable. Here we studied how an FFL responds to small external signal inputs at gene X, with particular attention paid to the fluctuation resonance (FR) phenomenon of gene Z. We found that for all coherent FFLs, where the sign of the direct regulation path from X to Z is the same as the overall sign of the indirect path via Y, the FR shows a regular single peak, while for incoherent FFLs, the FR exhibits distinct bimodal shapes. The results indicate that one could use small external signals to help identify the regulatory structure of an unknown FFL in complex gene networks. 展开更多
关键词 Gene regulatory network fluctuation resonance Feed-forward-loop
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Unsteady Turbulent Simulation and Pressure Fluctuation Analysis for Centrifugal Pumps 被引量:49
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作者 YUAN Shouqi NI Yongyan PAN Zhongyong YUAN Jianping 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2009年第1期64-69,共6页
The pressure fluctuation in the flow passage of both impeller and casing is addressed on design condition. The initial conditions for the unsteady turbulent simulation are resulted from the steady calculations, and th... The pressure fluctuation in the flow passage of both impeller and casing is addressed on design condition. The initial conditions for the unsteady turbulent simulation are resulted from the steady calculations, and the three dimensional unsteady turbulent simulation concerning the rotor-stator interaction is executed by a Navier-Stoke solver embedded with k -ε turbulence model and with appropriate moving interface boundary conditions. Detecting points are distributed in the flow passage in different radial and circumferential positions to capture the static pressure fluctuation character for one cycle of the impeller. The time-domain spectrums show that the static pressure curves are periodic and have five peaks and five valleys. With the radius increasing, the pressure fluctuation peak-to-peak values in the impeller are increasing, and reach the maximum value on the interface. In the casing flow passage, those values are about 7% of local static pressure except some ones near the tongue. The values become decreasingly in the diffuser pipe. The frequency spectrums transformed by fast Fourier transform (FFT) show that the dominant frequency is approximate with the blade passing frequency, and the pressure fluctuations in impeller passage have high frequency content while those in casing ones have no such information. 展开更多
关键词 centrifugal pump rotor-stator interaction unsteady turbulent flow pressure fluctuation
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Experimental Study of the Pressure Fluctuations in a Pump Turbine at Large Partial Flow Conditions 被引量:33
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作者 RAN Hongjuan LUO Xianwu +3 位作者 ZHU Lei ZHANG Yao WANG Xin XU Hongyuan 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2012年第6期1205-1209,共5页
Frequent shifts of output and operating mode require a pump turbine with excellent stability. Current researches show that large partial flow conditions in pump mode experience positive-slope phenomena with a large he... Frequent shifts of output and operating mode require a pump turbine with excellent stability. Current researches show that large partial flow conditions in pump mode experience positive-slope phenomena with a large head drop. The pressure fluctuation at the positive slope is crucial to the pump turbine unit safety. The operating instabilities at large partial flow conditions for a pump turbine are analyzed. The hydraulic performance of a model pump turbine is tested with the pressure fluctuations measured at unstable operating points near a positive slope in the performance curve. The hydraulic performance tests show that there are two separated positive-slope regions for the pump turbine, with the flow discharge for the first positive slope from 0.85 to 0.91 times that at the maximum efficiency point. The amplitudes of the pressure fluctuations at these unstable large partial flow conditions near the first positive slope are much larger than those at stable operating condtions. A dominant frequency is measured at 0.2 times the impeller rotational frequency in the flow passage near the impeller exit, which is believed to be induced by the rotating stall in the flow passage of the wicket gates. The test results also show hysteresis with pressure fluctuations when the pump turbine is operated near the first positive slope. The hysteresis creates different pressure fluctuations for those operation points even though their flow rates and heads are similar respectively. The pressure fluctuation characteristics at large partial flow conditions obtained by the present study will be helpful for the safe operation of pumped storage units. 展开更多
关键词 positive slope pressure fluctuation rotating stall pump turbine
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Trends in Temperature Extremes in Association with Weather-Intraseasonal Fluctuations in Eastern China 被引量:15
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作者 钱诚 严中伟 +1 位作者 符淙斌 涂锴 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2011年第2期297-309,共13页
Trends in the frequencies of four temperature extremes (the occurrence of warm days, cold days, warm nights and cold nights) with respect to a modulated annual cycle (MAC), and those associated exclusively with we... Trends in the frequencies of four temperature extremes (the occurrence of warm days, cold days, warm nights and cold nights) with respect to a modulated annual cycle (MAC), and those associated exclusively with weather-intraseasonal fluctuations (WIF) in eastern China were investigated based on an updated homogenized daily maximum and minimum temperature dataset for 1960–2008. The Ensemble Empirical Mode Decomposition (EEMD) method was used to isolate the WIF, MAC, and longer-term components from the temperature series. The annual, winter and summer occurrences of warm (cold) nights were found to have increased (decreased) significantly almost everywhere, while those of warm (cold) days have increased (decreased) in northern China (north of 40°N). However, the four temperature extremes associated exclusively with WIF for winter have decreased almost everywhere, while those for summer have decreased in the north but increased in the south. These characteristics agree with changes in the amplitude of WIF. In particular, winter WIF of maximum temperature tended to weaken almost everywhere, especially in eastern coastal areas (by 10%–20%); summer WIF tended to intensify in southern China by 10%–20%. It is notable that in northern China, the occurrence of warm days has increased, even where that associated with WIF has decreased significantly. This suggests that the recent increasing frequency of warm extremes is due to a considerable rise in the mean temperature level, which surpasses the effect of the weakening weather fluctuations in northern China. 展开更多
关键词 climate extremes EEMD weather-intraseasonal fluctuations modulated annual cycle global warming
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